Discuss the concept of the null hypothesis and its use in
data analysis.
Null hypothesis (H0) — it is a type of guess or speculation used in statistics that proposes that is no difference between some characteristics of population or data generating process. There is one more hypothesis that is called alternate hypothesis which proposes that here is a difference. Testing provides a way to reject null hypothesis but within a certain level of confidence. Null hypothesis cannot be proven.
Null hypothesis assumes that if the is any kind of difference exist between the chosen characteristics that is seen in a data is due to chance.
Statistical hypothesis is tested by using a four step process. The first step for the analyst is to state the two hypothesis form which only one can be right. The second step is formulation of an analysis plan that is an outline that how will be a data evaluated. Third step involve the carrying out the plan and analysis of sample data. And the final step is to analyze the result and if this result can reject the null hypothesis or not. It can be rejected with strong conclusion. The alternative conclusion that the results are explainable by chance is weak conclusion.
Let us take an example for more understanding, i.e. A school principal reports that students in her school scores an average of 7 out of 10 in examination.. The null hypothesis is population mean is 7.0.
To test this null hypothesis, we collect data of marks of 30 students for sample from the all student population of the school i.e. 300 and calculate the mean of that sample. We can then compare the calculated sample mean to the claimed population mean of 7.0 and attempt to reject the null hypothesis.
For the purposes of determining whether to reject the null hypothesis, the null hypothesis is assumed, for the sake of argument, to be true. Then the likely range of possible values of the calculated statistic (e.g., average score on 30 students’ tests) is determined under this presumption (e.g., the range of plausible averages may range from 6.2 to 7.8 if the population mean is 7.0).
Then, if the sample average is outside of this range, the null hypothesis is rejected. Otherwise, the difference is said to be “explainable by chance alone,” being within the range that is determined by chance alone.
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